linux-ext4 - [PATCH] ext4/mballoc: No need to generate from free list

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Date:   Thu, 24 Aug 2023 23:56:31 +0800
From:   Wang Jianjian <wangjianjian0@...mail.com>
To:     linux-ext4@...r.kernel.org, aneesh.kumar@...ux.vnet.ibm.com
Cc:     Wang Jianjian <wangjianjian0@...mail.com>
Subject: [PATCH] ext4/mballoc: No need to generate from free list

Commit 7a2fcbf7f85('ext4: don't use blocks freed but
not yet committed in buddy cache init) walk the rbtree of
freed data and mark them free in buddy to avoid reuse them
before journal committing them, However, it is unnecessary to
do that, because we have extra page references to buddy and bitmap
pages, they will be released iff journal has committed and after
process freed data.

Fixes: 7a2fcbf7f85('ext4: don't use blocks freed but not yet committed in buddy cache init')
Signed-off-by: Wang Jianjian <wangjianjian0@...mail.com>
---
 fs/ext4/mballoc.c | 27 ---------------------------
 1 file changed, 27 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 5b2ae37a8b80..b512a134a5fb 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -404,8 +404,6 @@ static const char * const ext4_groupinfo_slab_names[NR_GRPINFO_CACHES] = {
 
 static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
 					ext4_group_t group);
-static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
-						ext4_group_t group);
 static void ext4_mb_new_preallocation(struct ext4_allocation_context *ac);
 
 static bool ext4_mb_good_group(struct ext4_allocation_context *ac,
@@ -1274,7 +1272,6 @@ static int ext4_mb_init_cache(struct page *page, char *incore, gfp_t gfp)
 
 			/* mark all preallocated blks used in in-core bitmap */
 			ext4_mb_generate_from_pa(sb, data, group);
-			ext4_mb_generate_from_freelist(sb, data, group);
 			ext4_unlock_group(sb, group);
 
 			/* set incore so that the buddy information can be
@@ -4440,30 +4437,6 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 	return false;
 }
 
-/*
- * the function goes through all block freed in the group
- * but not yet committed and marks them used in in-core bitmap.
- * buddy must be generated from this bitmap
- * Need to be called with the ext4 group lock held
- */
-static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
-						ext4_group_t group)
-{
-	struct rb_node *n;
-	struct ext4_group_info *grp;
-	struct ext4_free_data *entry;
-
-	grp = ext4_get_group_info(sb, group);
-	n = rb_first(&(grp->bb_free_root));
-
-	while (n) {
-		entry = rb_entry(n, struct ext4_free_data, efd_node);
-		mb_set_bits(bitmap, entry->efd_start_cluster, entry->efd_count);
-		n = rb_next(n);
-	}
-	return;
-}
-
 /*
  * the function goes through all preallocation in this group and marks them
  * used in in-core bitmap. buddy must be generated from this bitmap
-- 
2.34.3